This work relates studies of whole organ preservation, including kidneys and liver. Intact organs are removed from experimental animals (dog, pig, monkey, rabbit, rats) and perfused with various solutions under investigation. The pH, electrolyte composition and other alterations of the perfusate and duration of the cold ischemic times are to be evaluated from the standpoint of a) survival following transplantation, b) release of lysosomal enzymes, c) hepatic cellular integrity and d) reticulo-endothelial function. In a parallel surgical experience, studies are outlined to determine effective grade of ischemia in reticulo-endothelial function in stump tail monkeys by clearance techniques using I-131 liquid emulsion, plasma opsonin levels and limulus assays of endotoxin detoxification using liver biopsies.